Dark vertical stripes in toilet bowl.

[adrianxw]

Not urgent!!! We moved to this house four years ago. The toilet bowl in the upstairs bathroom was seriously caked with yellow brown lime scale. Over the years, I have managed to get this off by attacking the material with weak household acids. There remains a dark grey to black, depending on the thickness, deposit over about a third of the bowl circumference organised as vertical stripes of various sizes, width and length. This is not Carbonate, it does not react with acid. Any idea what it is and ideally, how to remove it.

 

[adrianxw]

Not urgent!!! We moved to this house four years ago. The toilet bowl in the upstairs bathroom was seriously caked with yellow brown lime scale. Over the years, I have managed to get this off by attacking the material with weak household acids. There remains a dark grey to black, depending on the thickness, deposit over about a third of the bowl circumference organised as vertical stripes of various sizes, width and length. This is not Carbonate, it does not react with acid. Any idea what it is and ideally, how to remove it.

The marks resist strong acids also, concentrated sulphuric acid has no effect.

 

[oz-plumber]

The glazing on the pan may have been not done right or worn through to the porcelain / clay.

Probably easier to install a new pan than try and clean the old one

 

[Ben-gee]

I suspect someone in the past has used a physical means (ie metal scraper) to remove the limescale, this has scratched through the glaze - I’m afraid there’s nothing that can be done with it.

 

[rpm]

I think others may be right however if Acidwash 80 cant remove the marks then nothing will.

 

[WC1]

The marks resist strong acids also, concentrated sulphuric acid has no effect.

Id try hydrochloric rather than sulphuric ie spirit of salts. If that doesn't work then its physical damage as above.

 

[marvoni]

I'd also suggest spirit of salts (HCL) but take precautions, ventilate the room and wear eye protectection, gloves, apron etc, also mitigate risks for kids and pets. If that doesn't move the stains in 15 mins of less then I suspect nothing will.